RPM (engine speed) input - to what pin?

[ranz]

I´m building my own wiring harness and now when I was about to connect RPM to ECU, I don´t find to what pin to connect it?
The car is Audi S2 with 20VT engine.
I´m using standard VEMS ECU because I want to use my car with distributor, at first anyway
So what pin?

[gunni]

http://www.vems.hu/wiki/index.php?page=MembersPage%2FPhatBob%2FUserGuide

Use this guide for your wiring

[ranz]

http://www.vems.hu/wiki/index.php?page=MembersPage%2FPhatBob%2FUserGuide

Use this guide for your wiring

Is it just me or what? but I can not finde the RPM input pin?
I use the same guide for it... but there are only VR, hall, and other sensor inputs, but no RPM sensor input.

[rob@vems.co.uk]

I guess a lot is lost in translation, searching on Rev Counter (what we call them in the UK)
heres a couple of suggestions
http://195.159.109.134/vemsuk/forum/index.php/topic,1090.0.html
http://195.159.109.134/vemsuk/forum/index.php/topic,191.0.html

[mattias]

Key words : "primary trigger"

[ranz]

Key words : "primary trigger"

Primary trigger is the sensor next to RPM (rev counter) sensor, and the primary trigger is already connected. But where to connect the other sensor? or does it even need it?


Rob, S2 gets tacho signal from ecu, so I have no wire from sensor to tacho from where to take the signal. Right now I have connected the RPM signal from ecu to tacho from P259 ch0, but from where gets the ECU the engine speed?

[mattias]

The ECU gets the engine speed from the primary trigger.

Are you sure the "RPM sensor" you are referring to is not an RPM output to signal the gauge in the gauge cluster?

[ranz]

The ECU gets the engine speed from the primary trigger.

Are you sure the "RPM sensor" you are referring to is not an RPM output to signal the gauge in the gauge cluster?

Yes, I´m sure, see this picture of 3B sensors and stuff:
http://www.s2central.net/images/3B_ECU_Schematic.jpg
From left bottom, there is oxygen sensor, air mass sensor, reference sensor and engine speed sensor.
Top right there is output to tachometer.

[gunni]

Engine speed sensor will be the VR/Hall sensor.
i.e Trigger input.

[ranz]

Engine speed sensor will be the VR/Hall sensor.
i.e Trigger input.

But there is already also a hall sensor witch is connected to secondary trigger input.
Primary triger is the reference sensor
Secondary trigger is the hall sensor

Thats why this topic was made... I have all other inputs located, but i do not know where to connect the engine speed sensor

[mattias]

The "reference sensor" is for the single tooth on the flywheel, which masks the audi trigger. It is NOT the primary trigger.

[ranz]

The "reference sensor" is for the single tooth on the flywheel, which masks the audi trigger. It is NOT the primary trigger.

WTF did I really got all it wrong???
But the manual says:

Swapping the “Crank Home” pins:

         Inside the engine bay underneath the black plastic power output stage cover you'll find a row of electrical plugs.  Locate the 3 pin black female connector that leads to a black 3 pin male connector that goes to one of the VR sensors attached to the bell housing on the transmission.  This is the sensor that reads the pin on the flywheel, and two of the pins on the car harness need to be swapped.  To do this... etc.

So, from it I understand that primary trigger is the single tooth on flywheel.

Also, RPM sensor reads endless tooth on the flywheel, there is no missing tooth or anything else what is usable for somekinde of trigger???

[peter_jensen]

Some hints

http://www.vems.hu/wiki/index.php?page=MembersPage%2FPeterJensen/AudiSwiring


G28 pin 47 Engine speed sensor
G4 pin 49 Ref tooth
G40 Hall sensor 

[ranz]

Some hints

http://www.vems.hu/wiki/index.php?page=MembersPage%2FPeterJensen/AudiSwiring


G28 pin 47 Engine speed sensor
G4 pin 49 Ref tooth
G40 Hall sensor 

I have these schematics, but the concerne is: This schematic is NOT done yet and there can become errors.
And I have already made some modifications to that.
Also, can someone explane me how can be the primary trigger RPM sensor what reads endless tooth on flywheel???

[peter_jensen]

The schematic i made is working but it is not like the Vems web shop PnP.

The primary trigger senses the 135 teeth on the flywheel. The hall and sec trigger must come at the same time and when that happens the ecu knows that cyl1 is in compression I,e 62 BTDC and then we start counting the tooth on the flywheel.

The Audi trigger is complicated to understand for a newbie but don't pay attention how it works, just do like people tell you to do.

Peter